1. Field of the Invention
This invention relates to an air filter for electric welding, particularly to one able to block sparks and carry out filtration considerably well.
2. Description of the Prior Art
Metallic welding is very common in factories involving zinc welding, electric welding and heat treatment. Volatile fume produced by welding may contain heavy metals, such as lead, cadmium, manganese, nickel and chromium, and these metals may cause professional diseases such as fume fever, zinc fever, brass fever, asthma (poisoned by nickel), Parkinson disease (poisoned by manganese) and lung cancer (poisoned by chromium oxide), posing potential danger to human health. In order to protect persons exposed in such a contaminated environment, ventilation or wearing a proper respirator has been conventionally done so far. But, a lot of factories restricted by their structure cannot obtain good ventilation. Badly, a conventional ventilator with no additional screening function can merely expel the contaminated air elsewhere and make it dispersed in all direction, giving potential danger to people's life. Next, a respirator can only protect who wears it but not those who don't. Moreover, a worker wearing a respirator is prone to do only a lower quality job. Although, some factories use an industrial screen device while ventilating, but the screen is very easy to be clogged with oil and impurities produced during welding, having to replace with a new one very often, giving users much embarrassment indeed. Unfortunately, the screen used industrially does not have a function of extinguishing sparks that may cause a fire or an air explosion once it is sucked into the interior of the equipment.